Before objects containing metal or concrete which had been located in radioactively controlled areas, for example nuclear power plants, hospitals, nuclear research laboratories, or in areas contaminated as a result of accidents or disasters, can be removed from these areas, they must be tested to determine the degree of their radioactive emissions. The appropriate testing regulations prescribed by the Government require for example, among other criteria, a level test area, which should be no smaller than 100 cm.sup.2. It is furthermore not sufficient to make this test only in one spot of the object, it must be performed over its entire area. The test probes normally used herein have a size of 10.times.10 cm or 10.times.20 cm. As a rule, the test time per side of the probe is between 5 and 15 seconds. Each sector tested is marked on the object and is numbered and the test results are set down in a protocol. It can easily be imagined that with such a method two people will take approximately 15 to 20 minutes to test 1 m.sup.2 .
Added to this is the fact that many objects, such as furniture, pipes of various diameters, devices and control boxes, have such a complex shape that they cannot be tested at all under the current testing regulations. As a rule, such objects were considered to be radioactively contaminated, regardless of the intensity of their radiation, and disposed of accordingly. In the course of decontamination, regardless of the degree of contamination, the objects had to be disposed of, since they could not be tested because of their shape, even after contamination was removed, and thus decontamination would have been useless. Those objects which could be tested by the method according to the state of the art and which showed contamination of a specific area above the permissible level were decontaminated. Decontamination was performed by, for example, a so-called electro-chemical method, where the objects were placed in a phosphoric acid bath and approximately 10 to some 100 micrometers were removed by electrolysis. The test was subsequently repeated and, if the objects showed radioactivity below the permissible level, they were returned to future use in the form of scrap. The remaining electrolyte was contaminated and had to be disposed of or regenerated at great expense.
The prerequisites for tests to determine freedom from contamination are set very differently in the various countries. In Switzerland, the Hauptabteilung for Sicherheit der Kernanlagen (HSK) [Department for Safety of Nuclear Installations] is responsible for the nuclear power plants, in the field of medicine it is the Bundesamt fur Gesundheit [Federal Health Bureau]. Three different types of tests are performed for releasing radioactive materials. The following threshold values are applicable in Switzerland:
______________________________________ a. Surface contamination .alpha. emitters &lt; 1 .times. 10.sup.-5 Ci/cm.sup.2 other nuclides &lt; 1 .times. 10.sup.-4 Ci/cm.sup.2 b. Specific activity of .beta., .gamma. emitters &lt; 20 nCi/g .alpha. emitters &lt; 20 pCi/g c. Dose rate (net) in the HSK field &lt; 10 .mu.R/h in the SUVA field &lt; 50 .mu.R/h ______________________________________
There is the further prerequisite of proving that even under the most unfavorable conditions no impermissible exposure to radiation of persons not professionally exposed to radiation would occur in the course of the planned method of disposal or use. The following release criteria, listed in extract form, apply for the Federal Republic of Germany:
a. For waste:
&lt;10.sup.-4 -times the limit per gram (for example, for Co-60: 3.7 Bq/g) PA0 &lt;0.37 Bq/cm.sup.2 for other radioactive materials (.beta.,.gamma. emitters) PA0 0.037 Bq/cm.sup.2 for .alpha. emitters PA0 &lt;10.sup.-5 -times of the limit per gram
acc. to Appendix IV, Table IV, col. 4 in connection with Sect. 4, para. 4, No. 2e, StrlSch V [Order regarding Radiation Protection]
b. For waste and other re-usable residuals:
acc. to Appendix IX StrlSch V
c. For waste and other re-usable residuals: based on the Strahlenminimierungsgebot [Law for Reducing Radiation] Sect. 28 StrlSch V